Tunnel construction generally adopts full-section boring machine construction and drilling and blasting construction. Compared with the traditional drilling and blasting method, the tunnel boring machine construction has significant advantages of high mechanization degree, high construction speed and the like, so more than 80% of tunnels are constructed by adopting the boring machine construction in developed countries including Japan, United States, Europe and the like, and tunnel boring machines will be increasingly applied with continuous development of tunnel construction in China. Numerous engineering practices show that the tunnel boring machines have poor adaptability to the changes of geological conditions, and such geological disasters as water and mud outburst, collapse and the like always happen at bad geological sections, easily resulting in major accidents such as machine blockage and even machine destruction and death, etc. In order to avoid the geological disasters and safety accidents in construction of the tunnel boring machines, the most effective solution is to find out bad geological conditions in front of working faces in advance by adopting an advanced geological detection technology, so as to previously make reasonable disposal measures and construction plans.
However, the advanced geological detection method and technology in boring machine constructed tunnels are acknowledged difficulties in tunnel engineering at home and abroad, and the basic reason lies in particularity and complexity of the boring machine constructed tunnels:
(1) the tunnel boring machine has a complex metal structure and an electric system, and is quite serious in electromagnetic interference;
(2) the tunnel boring machine has huge size and occupies most tunnel space in back of a working face, so that the observation space available for advanced geological detection is very small; and
(3) the tunnel boring machine is high in excavation speed and close in procedure connection, and leaves a little time for the advanced geological detection. Under the restriction of these factors, good application of the advanced geological detection method often used in drilling and blasting constructed tunnels is difficult to realize in the boring machine constructed tunnels.
Thus, some advanced geological detection methods special for the boring machine constructed tunnels were proposed at home and abroad, but still have some problems:
(1) a BEAM (Bore-Tunneling Electrical Ahead Monitoring) system launched by Geohydraulic Data in Germany, wherein BEAM is a one-dimensional focusing induced polarization method, has short detection distance, and is highly influenced by electromagnetic interference, complex in installation of test equipment and time-consuming, and thus the construction progress is influenced;
(2) seismic wave advanced geological detection methods such as SSP (Sonic Softground Probing) and ISIS (Integrated Seismic Imaging System), wherein the observation mode is relatively simple, and the effective three-dimensional spatial observation mode is not adopted, so that the spatial positioning effect of an anomalous body is poor and the spatial resolution is also not ideal; and
(3) Chinese invention patents GEOLOGICAL ADVANCED PREDICTION METHOD SUITABLE FOR TBM CONSTRUCTION and TUNNEL BORING-ALONG SEISMIC ADVANCED DETECTION DEVICE AND METHOD TAKING BORING MACHINE AS SEISMIC SOURCE use a seismic while drilling method in petroleum logging for reference, proposed was advanced geological detection taking rock cutting signals as a seismic source, the former substantially uses a handling method of HSP in drill blast tunnels but does not adopt proper de-noising means for strong interference noise of rock breaking vibration of a boring machine, the latter mainly aims at a common cantilever-type boring machine in mine roadways, the cantilever-type boring machine has only one cutting head, only one seismic source signal reception sensor is arranged on a boring machine boom in back of the cutting head, whereas a tunnel boring machine has a huge cutter head and numerous hobs for breaking rock, and the rock breaking vibration difference between different hobs is large, so it is difficult to obtain accurate and comprehensive rock breaking vibration features by adopting the single sensor.
In conclusion, because of advantages in geological body characterization and positioning in combination with long detection distance, the seismic method is an indispensable method in advanced geological detection of boring machine constructed tunnels, but the existing seismic wave advanced detection method for boring machine constructed tunnels still has the following problems:
(1) the reception sensor is simple in spatial arrangement form, and does not adopt an effective three-dimensional spatial observation mode, so it is difficult to acquire accurate three-dimensional wave field information of surrounding rock, resulting in poor spatial positioning effect of an anomalous body, and problems such as missing report, erroneous report, misreport and the like are likely to occur;
(2) regarding an active source seismic method, it needs detection using the maintenance downtime of a boring machine as much as possible in order not to influence the normal construction of the boring machine, and the existing methods lack a quick installation device and method special for boring machine constructed tunnels, resulting in low detection efficiency and influencing the normal construction of the boring machine;
(3) regarding a rock breaking seismic source seismic method, on the one hand, the difference between the rock breaking mode of a boring machine cutter head and the single-head rock breaking mode of a cantilever-type tunnel boring machine for oil drilling and coal mine is not considered, i.e., the tunnel boring machine has a huge cutter head and numerous hobs for breaking rock, the rock breaking vibration difference between different hobs is large, whereas the existing method merely adopts a single seismic source sensor, so accurate and comprehensive rock breaking vibration features are difficult to obtain; on the other hand, the existing disposal method does not include special noise removal for seismic source signals and received signals respectively, so that the seism recording signal-to-noise ratio is relatively low and the detection precision is influenced; and
(4) in an active source seismic method, an air hammer or a magnetostrictor knocks a tunnel side wall or a working face to generate seismic wave at the maintenance downtime of the boring machine, and the excitation energy is relatively strong, so the method is suitable for long-distance advanced detection; the rock breaking seismic source seismic method uses the rock breaking vibration of the cutter head in the working process of the tunnel boring machine as a seismic source, and the excitation energy is relatively weak but contains a high proportion of transverse wave component, so the method is advantageous in short-distance accurate detection; the two methods are strongly complementary in working time and detection distance, the organic combination of the two methods can further improve the accuracy and the reliability of seismic method advanced prediction results, but the prior art does not well combine the two methods.